test(integration): skip refresh_operation_token tests on Bun

refresh_operation_token hangs indefinitely under Harper-on-Bun — CI
confirmed 6/9 tests pass then the runner cancels after ~2 h. Scope the
skip to just those two tests so the remaining 7 token-auth tests
continue to run on Bun.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: kriszyp